Drilling tool



June 14, 1955 o. E. DEMPSEY 2,710,740

v DRILLING Toor.

June 14, 1955 o. E. DEMPsEY DRILLING TOOL 3 Sheets-Sheet 2 Filed May 22, 1952 Fte. 3

June'l4, 1955 o. E. DEMPsEY 2,710,740

DRILLING TOOL Filed May 22, 1952 5 Sheets-Sheet 3 24 Fna. 7

IN VEN TOR.

O. EDE MP sx-:y

FIG. 5

United. States Patent .thee

2,710,743 Patented .lune i4, i955 DRILLING TOOL Oscar E. Dempsey, Tulsa, Okla., assigner, by mesne assignments, to Charles L. English, Tulsa, Okla.

Appiicaaen May z2, 1952, serial No. 289,339

7 claims. (ci. zes- 4.4)

This invention relates to a drilling tool, and more particularly but not by way of limitation, to a combination rotary drill bit and impact tool adapted to be utilized for the drilling of an oil well.

In the drillingr of oil wells, and particularly with rotary drill tools, it has been found that as the depth of the well bore increases, the formation strata of the well usually becomes more difficult to penetrate, and under such conditions the rotation of the rotary drill bit is somewhat retarded. Consequently in a hard shale strata penetration is extremely dithcult. A hard penetration condition usually causes a rapid wearing of the drill bit teeth, bearings and other parts of the rotary tool, as well as very slow penetration. Furthermore, the rotary drill bits in addition to rapid wear, usually will become damaged, and must he pulled from the well bore and replaced with a new rotary bit. In difficult shale conditions it has been found that the pulling and replacement operation is necessitated for approximately every foot or two of penetration, which is inefficient and costly.

The present invention is generally concerned with a combined drilling apparatus utilizing an impact tool in conjunction with a rotary drilling tool wherein the percussive action of the impact tool is provided oy a hydraulically actuated and valve controlled piston, wherein the circulating drill fluid is utilized for actuating the piston in a striking blow against the impact tool, thereby causing a breaking up and crushing of hard formations by a percussive action in order to facilitate the biting engagement of the rotary tool and permit the rotary tool to penetrate the harder formations in an eflicient and expeditious manner with a modicum of wear and tear, as well as eliminate any abnormal pulling or replacement of the rotary tool.

It is an important object of this invention to provide a well drilling tool that will decrease the cost of the drilling operation by increasing the foot penetration per hour for the average rotary cutter or drill.

And still another object of this invention is to provide a well drilling tool having a combined rotary and rectilinear movement in order to facilitate the penetration of hard shale formations during the drilling operation.

Another object of this invention is to provide an apparatus for drillinft wells which includes an outer rotary drilling tool, and an inner impact or percussive tool wherein circulating well fluid is utilized to actuate a reciprocating member into striking contact with the impact tool simultaneous with the rotation of the rotary tool in order to facilitate the penetration of the rotary tool in hard shale formations.

And still another object of this invention is to provide a combined rotary and impact tool for the drilling of oil wells that is operable to rapidly and efcicntly break up and crush any hard shale formations without materially reducing the cutting speed or efficiency of the drilling tool.

Another object of this invention is to provide a tool for the drilling of oil wells having a hydraulically actuated impact tool operating during the usual rotation of a rotary tool wherein the operation of the impact tool is automatic and does not require any special manipulation or handling of the drilling string.

And still another object of this invention is to provide a rotary drilling tool for oil wells which is normally capable of operation on the substantial area of the hole bottom, yet nevertheless permits an impact tool to pass completely through the rotary drilling tool while in position in the well bore in order to break up or crush any hard shale formations and facilitate the biting engagement of the rotary drilling bit therewith.

And still another object of this invention is to provide a combined drilling tool which is eiiicient and simple in its operation, durable and easy to manufacture.

Other objects and advantages of the invention will be evident from the following detailed description read in conjunction with the accompanying drawings which illustrates my invention.

ln the drawings:

Figure l is a sectional elevation view showing the tool secured in suspended relationship at the bottom of a well drilling string.

Figure 2 is a sectional elevational View slightly enlarged of the actuating valve mechanism.

Figure 3 is a sectional elevation view of the modified form of the tool.

Figure 4 is a modied view similar to Figure 2 showing the valve mechanism in another position of operation.

Figure 5 is a partial schematic view in sectional elevation of the apparatus shown in Figure l.

Figure 6 is a sectional view taken on lines A-A of Figure l.

Figure 7 is a similar view taken on lines C-C of Figure l.

Figure 8 is a similar view taken on lines D-D of Figure l.

Figure 9 is a similar View taken on lines B--B of Figure l.

Referring to the drawings in detail and more particularly Figures l and 2, reference character 2 designates a drill collar disposed at the lower end of a drill stem disposed in a well bore (not shown). An adapter 3 for the drilling tool is secured at 4 to the collar in any conventional manner, such as tool joint threading and the like (not shown). The drill collar 2 is provided with a central bore 5 in alignment with a bore 6 of the adapter 3 for a purpose as will be hereinafter set forth. The adapter is provided with a reduced portion 7 to which is secured a casing 8 extending vertically downward therefrom into threaded connection (not shown) with a lower adapter 9. lt is to be understood that unless otherwise stated the connections between the various elements are threaded connections. The adapter 3 has a reduced neck portion 1l connected to a valve housing 12, which in turn is connected at 13 to an inner casing 14 disposed in spaced relationship relative to the casing 8, and providing an annulus 15. r[he inner tubing 14 extends vertically downward into communication with a lower piston block or manifold 16 as will be hereinafter set forth. The piston block i6 is provided with a reduced portion 17 connecting with the adapter 9 in such a manner to compress a circular sealing washer 13 of rubber or like material disposed on a shoulder portion 19 of the adapter 9. The adapter 9 is provided with a tapered bore 2) for connection with any suitable type drilling bit 21 having the usual rotary or cone drill bit members 22.

The valve housing 12 extends downwardly in the tubing 14 into connection with a pilot valve housing 23- (Figs. l and 2). A piston head 24 is disposed in vertical spaced relation below the pilot Valve housing 23 and is provided with a central bore 25 having a ared or tapered portion 26 providing a connection with a piston unit 27 partially disposed therein. The piston unit 27 extends downwardly from the piston head 24 into a central bore 2S of the manifold 16 for a purpose as will be hereinafter set forth. The bore 23 increases in diameter adjacent the reduced neck portion 17 for receiving a downwardly extending sleeve 29, which in turn extends through the apertured adapter 9 and into the apertured drill bit 21. A bushing 30 is interposed between the outer periphery of the sleeve 29 and the inner periphery of the rotary tool 21. The bushing has a plurality of circumferentially spaced passageways 31 for a purpose which will be hereinafter set forth. The upper portion of the sleeve is increased in diameter at 32 for receiving an enlarged flange portion 33 of a circular' impact tool 34 extending downwardly through the sleeve 29, and outwardly therefrom to a position below the drill 21. The lowermost end of the impact tool 34 is provided with suitable drill cutters 35 or the like for a purpose as will be hereinafter sct forth.

Considering the upper portion of Pigs. l and 5. above the top of piston block 24, as the top of the tool unit, it will be apparent that the valve housing 12 (Fig. 2) is provided with a cutaway portion 36 in which is disposed an upper ring 37 having cutaway tapered surfaces 3S acting as an upper valve seat for the extension valve 39. A lower ring 40 is disposed in the housing 12 and is provided with tapered portions 41 acting as a lower valve seat in a manner as will be hereinafter set forth. The extension valve 39 comprises a flange portion 42 having a reduced body 43 connected with a recessed neck 44 of a main valve body 45. The neck 44 extends through the lower ring 40, and is increased in diameter to provide the main valve body 45 which in turn is provided with a reduced neck portion 46 at its lower or opposite end for a purpose as will be hereinafter set forth. The extension valve 39 is provided with a transverse port 47 in communication with a centrally disposed longitudinal port 48 in turn communicating with a passageway 49 communicating with longitudinal ports 50 in the main valve 45. The longitudinal ports 50 are in communication with a central bore 51 of the main valve body 45.

A pilot valve 55 is disposed in the bore 51. The lower end of the valve 55 is provided with a reduced neck 56 connecting with a yoke 57 in a manner similar to a ball and socket connection. A valve rod 58 is secured to the socket or yoke 57 and extends downwardly through an aperture 59 provided by inwardly extending shoulders 60 of the valve housing 23. The valve housing 23 is recessed at 61 for receiving a guide sleeve 62 having a bushing 63 surrounding the rod 58. A coupling 64 is disposed in the sleeve 62 and connects with one end of the rod 58 (Fig. 2).

The valve rod 58 is connected through the coupling 64, with a lower valve rod 65 (Fig. l) extending downwardly into the bore 25 of the piston head 24, and into the cavity 66 of the pistou 27. The lower end of the rod 65 is provided with a nut 67 for a purpose as will be hereinafter set forth. The upper portion of the piston head bore is increased in diameter at 68 for receiving a sleeve 69 having a anged portion 70. An outer sleeve 71 has a slip fit with the sleeve 69, and is provided with an outwardly extending flange 72 for maintaining a plurality of packing rings 73 surrounding the outer sleeve 71. The inner periphery of the sleeve 69 is provided with inwardly projecting shoulders 74 for a purpose as will be hereinafter set forth. A circular sealing gasket 75 is interposed between the sleeve flange 7i), and the hanged portion 72 of the sleeve 71. A helical spring 76 is disposed in the bore 25 of the piston head 24 and encircles the extension valve rod 65. The spring 76 is provided with an upper nut 77, and a lower nut 7S for anchoring the spring 76 between the shoulders 74 and the top of the piston 27.

It will also be apparent that the position of the piston 27 relative to the shoulders 74 limits the travel of the helical spring. The bore 28 of the piston block 16 has an increased portion 79 receiving a piston liner S0 and packing 80a held therein by a suitable nut 81. The outer periphery of the block 16 is provided with a circular groove S2 in communication with a plurality of circumferentially spaced, longitudinally drilled bores or apertures 83, provided at the lower end of the block 16. At a point below the groove 82, the block 16 is provided with a plurality of vertically spaced circumferential grooves 84 for receiving the circular packing rings 85. The block 16 is also provided with a radial or transverse bore 86 in communication with the bore 28, and in which is disposed any suitable check valve 87 for a purpose as will be hereinafter set forth. The lower portion of block 16 is provided with a milled slot 92 permitting communication between bore 86 and annulus 82a. The outer periphery of the block 16 above the rings 85 is spaced from the casing 8 to provide an annulus 92a. The longitudinal bores 83 of annulus 82u are in communication with a plurality of longitudinal passageways 88 provided in the adapter 9. which in turn communicate with the bores 89 and 31 and through the rotary bit unit 21. In this manner it will be apparent that flow of the circulation well duid can be maintained throughout the unit in the usual manner.

Operation During the drilling of an oil well, circulation uid pumped from the well surface (not shown) is constantly present in the bore 5 of the drill stern. The drilling uid is directed through the bores 5 and 6 and a port 91, communicating with the passageway or annulus 15, wherein it is directed through a port 93 into a chamber 94 below the piston head 24, and the packing cups 73. It is apparent that iluid present in chamber 94 may ow through the annulus 92a into communication with annular groove 82, and the passageways 83, 88 and 89 to be discharged from the lower end of the bit 21 and thereby provide circulation through the unit. The valve 39 as shown in Fig. l is in seating relationship with the upper valve ring 37 and as such, provides an exhaust pressure condition in chamber 97 as will be hereinafter set forth. With an exhaust condition in chamber 97, the pressure of the drilling fluid present in chamber 94 will act against the lower face 98 and cups 73 of piston head 24 to cause an up-vertical movement thereof for simultaneously moving the piston 27 upwardly through the piston block or manifold 16. Continued upward movement of the piston 27 and the piston head 24 positions the upper spring nut 77 into contact with the lower face 99 of the coupling member 64. The various elements positioned as set forth in Fig. 2 for the bore 51 and chamber 101 of the main valve 45 are maintained due to the presence of drilling uid discharging through passageways 49 and 50 as will be hereinafter set forth. However, as soon as the nut 77 contacts the coupling 64, the spring 76 is placed under compression, which is increased by continued upward movement of piston 27 to subsequently cause movement of the pilot valve 55 through the bore S1. The movement of the pilot valve 55 upward will close the input ports to the input uid pressure from passageway 47, 49 and 50. The chamber 101 communicates with bore 51 through a longitudinal forked passageway provided at 102 in valve 55. The movement of the pilot valve 55 to close off the ports 100 simultaneously opens the transverse ports 103 provided in valve 45 into communication with the high pressure condition in chamber 101, whereby pressure fluid in chamber 101 is exhausted through the ports 103, annulus 104, communieating with an exhaust passageway 105 drilled in the valve housing 12, and in turn communicating with a drilled passageway 106 in the adapter 3 providing communication with the well bore.

As soon as the high pressure condition in chambers 51 and 101 is exhausted to provide a low pressure condidition therein, the pressure of the drilling uid reacts against the upper face of the extension valve 39, and

2 moves the valve 39 downwardly away from its seat 38, and into a seating relationship with the seating ring 4G. This movement of the valve 39 opens the port 11G in communication with the chamber 97 thereby discharging the drilling fluid into contact with the uppermost portion or the power face of the piston head 24 as disclosed generally by the member 72 and cups 73. As soon as the pressure builds up in chamber 97 it will move the piston head 24 downward in a power or working stroke with a simultaneous movement of the piston 27 in the bore 28. T he downward movement of the piston head 24 will displace drilling fluid present in chamber 94 below the piston head 24, through the orifice 93, annulus and through the orifice 91. This displacement is effected by the larger cross sectional area of the upper portion or power face of the piston head 24 relative to the cross sectional area of the lower portion as disclosed by the annulus 94, relative to the piston 27. The downward movement of the piston head 24, and piston 27, is increased in momentum and inertia to increase its speed, thereby increasing the impact or blow of the piston against the iiange portion 33 of the impact tool 3d. it will he apparent that the movement of the impact tool 54 downward is independent of the continuous rotation of the outer casing S and the rotary drilling of tool 21.

As clearly shown in Fig. 5, the downward movement of the piston head 24 positions' the valve rod nut 67 into contact with the spring anchor nut 73 thereby placing the spring 76 under compression as shown, whereupon continued downward movement of the head 24 will cause the spring 76 to move the pilot valve 55 downward in the bore 51 and close otl` the exhaust ports 1133. With the pilot valve moved to this position, the input ports lll are now in communication with the chamber 51 to permit the drilling lluid to be directed through the transverse ports 4? of the valve 39, longitudinal port 43 communieating with the longitudinal ports 5@ and the intake ports 150. Continued flow of the drilling fluid will build up the pressure in the chambers 51 and 151 and when increased suiliciently will overcome the thrust of the input duid pressure at valve 3% due to the increased cross sectional area of the valve relative to the extension valve 39, whereby the valve will be moved to an upward position as shown in Fig. 2, with a simultaneous movement of the valve 39 into a seating relationship with the upper seat 37 for closing orf the supply liuid pressure to port 11d. The supply pressure iluid discharging through port 91, annulus 15, and chamber 94, will again cause movement of the piston head and piston 2'7 in an upward, or suction stroke in order to position the piston for another impact stroke against the tool 3d.

During the upward movement of the piston head 24, the liquid in chamber 97 is open to discharge well bore pressure through the passageway 11d communicating with passageway 46a in turn communicating with the annulus 104 and passageways 155 and 106. The force of high pressure input iluid entering chamber 94 by way of ports 91, annulus 15' and ports 93 forces the liquid existing in chamber 97 into the lower pressure of the well bore, providing that the cross-sectional area of chamber 97 times the well bore pressure in sufficient quantity to overcome frictional resistance and the energy necessary to move the pilot valve into the higher pressures existing in chambers 101 and 51.

It will be apparent that during the downward stroke of the piston 27 and iluid pressure that may be present in the bore 28 below the piston 27 is displaced through the check valve 37, and discharges through the passageways 92 and S8, and from rotary bit 21, thereby providing a cavitation or exhaust condition in the bore 28 below the piston and during the upstroke of the piston. The cavitating of the bore 28 substantially relieves any pressure condition in the bore 28 for the next downward stroke of the piston. The piston 27 is thus moved downward by the pressure of the drilling fluid under pressure of a surface pump (not shown), and the hydrostatic head of iluid in the drill stem acting against the top of the piston head 24, so that an increased pressure by the product of these combined pressures will move the piston 27 downward with an increased momentum into contact with the tool 34 at an increased force or impact to cause an eiiicient operation of the cutters 35. It will thus be apparent that the greater the depth of the well bore and the greater the hydrostatic head, the greater will be the resultant impact of the piston 27 against the impact tool 34.

In Figs. 3 and 4 is shown a modification of the tool, wherein the control valve unit, comprising the valve housing 12, pilot valve housing 23 and the respective valve elements therein are substantially the same as in the preferred embodiment, as will be hereinafter set forth. The drill string 4 is shown connected with an adapter secured thereto. A tubular housing 116 is secured to the lowermost portion of the adapter 115, and extends vertically downward into a connection with a lower retaining nut 117. A combined impact and rotary tool 118 is disposed in the nut 117 as will be hereinafter set forth. The adapter 115 has a drilled passageway 119 providing communication between the drill stern 4 and a chamber 121) disposed below the adapter 115. A centrally disposed recess 121 is provided in the adapter 115 and communicates with a transverse passageway 122. A tubing 123 of smaller diameter is secured in the recess 121 and extends vertically downward from the adapter 115 through a bearing member 124 secured to an inner tubing 125. The tubing 125 is disposed in spaced relation relative to the casing 116, and extends vertically downward into connection with a ange portion 126 of a piston member 127, as will be hereinafter set forth.

The lower end of the small tubing 123 is disposed in a recess of the valve housing 128. The outer periphery of the valve housing is provided with packing rings 129, as in the preferred embodiment. A port 131i is provided in the housing 128 providing communication between a chamber 131 and a cavity or recess 132 in the housing 128. The upper housing 128 is connected at 133 with the valve housing 12, containing the extension valve 39, main valve 45 and pilot valve 55 in substantially the same arrangement as disclosed in the preferred embodiment. Furthermore, the upper seating ring 37 and a lower seating ring 41 are shown. The pilot valve stem 57 extends downwardly from the pilot valve 55 into communication with the coupling 64. The valve extension rod 65 extends into a recess 135 of the piston 12.7, as clearly shown in Fig. 3. The bore or recess 135 is provided with inwardly projecting shoulders 136 acting as an anchor for one end of the spring nut 137, however the shoulders provide an aperture 136a of suiicient diameter to permit passage of the coupling nut 64 and guide sleeve 170. A helical spring 13S is disposed in the bore 135 and encircles the extension rod 65. The bore 135 is provided with shoulders 135a for anchoring a lower spring nut 139. The extension rod 65 extends below the nut 139 into the smaller bore or recess 140 communicating with the recess 135. A nut 141 is secured to the end of the rod 65 for a purpose as will be hereinafter set forth.

1t will be apparent that the main valve mechanism, valve rod and pilot valve, the actuating spring member in their relation to the piston member 127 is substantially the same as that disclosed in the preferred embodiment. The piston 127 extends vertically downward in the casing 116, and the lower end of the piston is provided with a flange portion 142 of increased diameter cooperating with a bushing 143 of still greater diameter and encircling the piston 127. The ilange 142 is provided with a plurality of circumferentially spaced, longitudinally drilled passageways 144 having an outlet through a port 145 below the bushing 143 and nut 143e. The lowermost 7 portion 146 of the piston 127 is disposed in spaced relation with the casing 116 to provide an annulus 147. The portion 146 of the piston is normally maintained in contact relation above the upper face 148 of the impact tool 118.

As previously referred to, the tool 118 is slidably disposed in spaced relation in the casing 116 by the nut 117. A shoulder 149 cooperates with a vertically spaced bearing ring 150 to maintain packing rings 151 therebetween on the outer periphery of the tool 118. The tool is provided with a bore 152 having forked passageways 153 communicating with the chamber 154. The bore 152 communicates with a bore 155 of larger diameter provided in any suitable type rotary or roller drill tool 156 secured in the tapered bore 15`6a of the tool 118. The bore 155 extends through the bit to allow communi cation with the well bore. An apertured collar 157 is secured to the inner periphery of the casing 116 and provides an anchor for one end of a helical spring 158 encircling the smaller diameter of the piston 127. The opposite end of the helical spring is anchored against the flange 142 thereof. The collar 157 is provided with an aperture 159 permitting longitudinal movement of the reduced body portion 127a of the piston 127 therethrough.

ln operation of the modified apparatus (Figs. 3 and 4), the supply fluid pressure flows through passageway 119 into chamber 120, and hence through a plurality of circumferentially spaced ports 160 into the chamber 131, port 130, bore 132 and a port 161 into chamber 162. It will be apparent that the drill fluid may also discharge through the annulus 163 and into a chamber 164 below the piston flange 126. The aperture 159 and the drilled passagev/ays 144 permit discharge of the fluid to the chamber 154 below the piston 127. ent that the input pressure of the drilling fluid is maintained on both sides of the piston 127, that is, in charnbers 162, 120, 164 and 154, and downward movement of the piston 127 will be caused by the tension of the spring S as will be hereinafter set forth. As shown in Fig. 3. the arrangement of the valve elements is such that the piston 127 is moving in a downward stroke, to contact the face 14S of the tool 118, whereby the spring 138 will cause actuation of the pilot valve 55 in the same manner as in the preferred embodiment to close off the exhaust ports 103 and open the input ports 50 to the bore 51, thereby causing an increase in pressure in bore 51 and chamber 101 by permitting drilling fluid communication with ports 47 and 48 to flow thereinto.

As soon as the pressure in bore 51 and chamber 101 is t increased, the valve 45 will be moved upwardly to close the extension valve 39 against the upper seating ring 37 thereby blocking oi port 161 to input pressure of the drilling fluid. With the various valve elements changed to the position such as shown in Fig. 2, any pressure condition in chamber 162 is exhausted through port 161 (or 110 in the preferred embodiment) around the neck portion a of the extension valve 39 into communication with the exhaust ports 104, 105 and 106 where it is discharged through the tubing 123 and port 122 into the well bore.

With an exhaust pressure condition in chamber 162, a high pressure condition will be present in chamber 154 due to the pressure of the input pressure fluid previously discharged thereto and will react against the piston section 146 to move the piston 127 vertically upward, simultaneously placing the spring 158 under compression between the anchoring points 157 and 142. Continued upward movement of the piston 127 also places helical spring 138 under compression to subsequently cause a movement of the pilot valve 55 upward in a manner similar to that of the preferred embodiment, particularly moving the valve 55 to a position closing the input port 100 to chamber 51 and opening the exhaust ports 103 to charnbers 51 and 101. lt will be apparent as soon as the It will thus be apparprevious high pressure condition in chambers 51 and 101 is bled through the exhaust ports 104, 105, 106, etc., the drilling fluid pressure acting against the face of the valve 39 and valve 45 to a position where the valve 39 is disposed against the lower seating ring 40, thereby opening port 161 (Fig. 4) to the input pressure of the drilling fluid. which is then permitted to discharge through the port 161 and to the chamber 162, thereby increasing the pressure condition in chamber 162 to equalize or balance the pressure condition therein relative to the pressure condition in 154. As soon as the pressure in chamber 162 builds up sufficiently to cause an equalization or balancing of the pressure condition in chambers 162 and 154, the helical spring 158 which has been placed under compression will then exert tension against the flange 142 causing a downward movement of the piston 127 for an impact stroke with the face 148 of the tool 11S. During the downward movement of the piston 127 liquid present in chamber 154 is displaced therefrom, and permitted to flow through the annulus 147, ports 144, aperture 159, annulus 163 into chamber 131 whereupon opening of port 161 it will be directed into chamber 162, as previously set forth. lt will thus be apparent that during the downward stroke of the piston there is a transfer of the high pressure liquid from chambers 154 and 131 to chamber 162. As the spring 15S exerts its tension and moves the piston 127 downward, the spring 138 is also placed under further tension to cause movement of the pilot valve through the rod downward in the same manner as in the preferred embodiment. lt will be apparent that during the displacement of the uid from the chamber 154, all the uid need not be transferred to chamber 162 as a portion thereof is discharged through the passageway 152 and bore 155 of the bit 156 in order to maintain a continuous circulation of the drill uid for the removal of cuttings, as is usual in the rotary drilling of an oil well. It will thus be seen that the modified embodiment shown in Fig. 3, eliminates the cavitating of a chamber below the reciprocating piston but in lieu thereof, partially transfers the liquid pressure in chamber 154 to a chamber 162 above the piston unit 127 during the power or downward stroke of the piston. In this manner, the spring 158 is the main actuating medium for the power or impact stroke of the piston 127 by effecting a fluid transfer from chamber 154 to 162. However the continuous flow of fluid through the apparatus to effect a desired fluid circulation in the well bore relieves the spring 158 of a portion of its duty by allowing the continuous flow from port 119 to enter cavity 162 directly while liquid leaves chamber 154 to the well bore. This condition creates an added pressure surge to develop in chamber 162.

From the foregoing it will be apparent that the present invention provides a combination drilling apparatus utilizing a percussive or impact tool in conjunction with a rotary drilling tool at the end of a drill string in order to break up and crush hard formations by a percussive action, and thus facilitate the biting engagement of the rotary tool through hard formations. Furthermore it will be apparent that providing for an easier penetration through hard formations will also eliminate considerable Wear and tear on the rotary tool and consequently eliminate numerous pulling jobs and replacement of the rotary tool, thereby effecting a saving in the drilling apparatus as well as a saving in labor and the overall cost of the drilling operation. The impact tool by breaking up any smooth contour that may be formed by the rotary drilling operation, thereby providing a better Contact for the teeth of the drill bit with the broken formation and thus facilitates the ease of the drilling operation.

It will also be apparent that the present invention provides a drilling apparatus utilizing an impact tool in conjunction with any suitable rotary drilling cutter or tool wherein the impact tool is actuated by a reciprocating member which, in turn, is hydraulically actuated by the medium of the circulating well pressure fluid, and movement of the reciprocating member is actuated by a hydraulic control means for ycontrolling the direction of flow of the circulating iiuid to cause actuation of the reciprocating member.

This application is a continuation of my copending application Serial No. 8,101, tiled February 13, 1948, now abandoned.

While there has been described what is at present considered a preferred embodiment of the present invention and a modification thereof, it will be apparent to those skilled in the art that various other modifications and changes may be made without departing from the essence of the invention, and it is intended to cover herein all such modifications and changes as come within the true scope and spirit of the appended claims.

I claim:

1. A fluid-actuated well drilling tool comprising: a main housing adapted to be attached to a drill string through which drilling fluid is circulated in a well bore; a cylinder member in said housing and a piston member in said cylinder, one of said members being reciprocable, said piston having an extension on one end thereof projecting through an end wall of said cylinder, said extension being of less diameter than said piston to provide an annular face on said end of said piston and define with said cylinder an annular space in communication with said annular face; said cylinder having a port therein in constant open communication with said annular space and with the interior of said drill string whereby to constantly subject said annular space and the adjacent annuiar face of said piston to the pressure of the drilling fiuid in said drill string; a valve housing in said main housing and having a iirst fluid passage communicating with the cylinder space at the end of said piston opposite said annular space, a second fluid passage communicating with the interior of said drill string, and a third uid passage communicating with the exterior of said main housing; a movable valve in said valve housing arranged to communicate said first iiuid passage alternately with said second and said third fluid passages and cause reciprocation of said reciprocable member; means interconnecting said valve and said reciprocable member to move said valve in timed relation to the reciprocation of said member; and a percussion bit at the lower end of said main housing arranged to be contacted and actuated by said reciprocable member.

2. A fluid-actuated well drilling tool comprising: a main housing adapted to be attached to a drill string through which drilling fluid is circulated in a well bore; a cylinder in said housing and a piston reciprocable in said cylinder; a hammer element extending downwardly from said piston through the lower end of said cylinder, said hammer element being of less diameter than said piston and defining with said cylinder an annular cylinder space beneath said piston; said cylinder having a port therein adjacent the lower end thereof in constant open communication with said annular space and with the interior of said drill string whereby to constantly subject said annular space and the adjacent annular face of said piston to the pressure of the drilling fluid in said drill string; a valve housing in said main housing and having a iirst fluid passage communicating with the cylinder space above the piston, a second fluid passage communicating with the interior of said drilling string, and a third iiuid passage communicating with the exterior of said housing; a movable valve in said valve housing arranged to communicate said first fluid passage alternately with said second and said third fluid passages and cause said piston to reciprocate in said cylinder; means interconnecting said valve and said piston to move said valve in timed relation to the reciprocation of said piston; and a percussion bit at the lower end of said main housing, said bit having a striking surface subjected to impact by said hammer element on downward movement of said piston.

3. A duid-actuating well drilling tool comprising: a

main housing adapted to be attached to a drill string through which drilling fluid is circulated in a well bore; a cylinder member in said housing and a piston member in said cylinder, one of said members being reciprocable, said piston having an extension on one end thereof projecting through an end wall of said cylinder, said extension being of less diameter than said piston to provide an annular face on said one end of said piston and define with said cylinder an annular space in communication with said annular face; said cylinder having a port therein in constant open communication with said annular space and with the interior of said drill string whereby to constantly subject said annular space and the adjacent annular face of said piston to the pressure of the drilling fluid in said drill string; a valve housing carried by said piston and having a first iiuid passage communicating with the cylinder space at the end of the piston opposite said annular space, a second uid passage communicating with said annular space, and a third fluid passage communicating with the exterior of said main housing; a movable valve in said valve housing arranged to communicate said first fluid passage alternately with said second and third fluid passages and cause reciprocation of said reciprocable member; means interconnecting said valve and said reciprocable member to move said valve in timed relation to the reciprocation of said member; and a percussion bit at the lower end of said main housing arranged to be contacted and actuated by said reciprocable member.

4. A fluid-actuated well drilling tool comprising: a main housing adapted to be attached to a drill string lthrough which drilling fluid is circulated in a well bore; a cylinder member in said housing and a piston member in said cylinder, one of said members being reciprocable, said piston having an extension on one end thereof projecting through an end wall of said cylinder, said extension being of less diameter than said piston to provide an annular face on said one end of said piston and denne with said cylinder an annular space in communication with said annular face; said cylinder having a port therein in constant open communication with said annular space and with the interior of said drill string whereby to constantly subject said annular space and the adjacent annular face of said piston to the pressure of the drilling fluid in said drill string; a valve housing in said main housing and having a first fluid passage communicating with the cylinder space at the end of said piston opposite said annular space, a second tiuid passage communicating with the interior of said drill string, and a third iiuid passage communicating with the exterior of said main housing; a movable valve in said valve housing arranged to communicate said first fiuid passage alternately with said second and said third iiuid passages and cause reciprocation of said reciprocable member; means interconnecting said valve and said reciprocable member to move said valve in timed relation to the reciprocation of said member; a rotary drilling bit secured to the lower end of said main housing and having an axial opening therethrough; and a percussion bit slidably mounted in said axial opening and having an impact surface subjected to impact of said reciprocable member upon reciprocation of said member.

5. A fluid-actuated well drilling tool comprising: a main housing adapted to be attached to a drill string through which drilling fluid is circulated in a well bore;

a cylinder in said housing and a piston reciprocable in said cylinder; a hammer element extending downwardly from said piston through the lower end of said cylinder, said hammer element being of less diameter than said piston and defining with said cylinder an annular' cylinder' space beneath said piston; said housing and said cylinder cooperating to define an annular fluid passage communieating at one end with the interior of said drill string; said cylinder having a port therein adjacent the lower end thereof providing constant open communication between said annular uid passage and said annular cylinder space whereby to constantly subject said annular space and the adjacent annular face of said piston to the pressure of the drilling uid in said drill string; a valve housing in said main housing and having a rst uid passage communicating with the cylinder space above the piston, a second uid passage communicating with the interior of said drill string, and a third fluid passage communicating with the exterior of said housing; a movable valve in said valve housing arranged to communicate said rst iuid passage alternately with said second and said third fluid passages and cause said piston to reciprocate in said cylinder; means interconnecting said valve and said piston to move said valve in timed relation to the reciprocation of said piston; and a percussion bit at the lower end of said main housing, said bit having a striking surface subjected to impact by said hammer element on downward movement of said piston.

6. A drilling tool comprising a housing attached to a rotary drill string disposed in a well bore, a rotary cutting tool secured to the lower end of the housing and having an axial opening therethrough, an impact tool disposed in the housing and adapted to be slidable through the axial opening, reciprocating piston means disposed in the housing and responsive to the pressure of the circulating well uid for moving in a power stroke into contact with the impact tool to cause a longitudinal percussive movement thereby, valve means for controlling the reciprocation of the piston, said valve means comprising a valve housing disposed in the rst mentioned housing, a main valve and a pilot valve disposed in the valve housing, a valve rod carried by the pilot valve and adapted to be actuated by the piston for moving the pilot valve in timed relation to the movement of the 1.2 piston, ports in the pilot valve for directing the well fluid to the main valve to control movement of the main valve, and a passageway in the valve housing adapted to be alternately opened and closed by the main valve in alternate positions thereof to control application of the well fluid to the piston.

7. A drilling tool comprising a housing attached to a rotary drill string disposed in a well bore, a rotary cutting tool secured to the lower end of the housing and having an axial opening therethrough, an impact tool disposed in the housing and adapted to be slidable through the axial opening, reciprocating piston means disposed in the housing and responsive to the pressure of the circulating well uid for moving in a power stroke into contact with the impact tool to cause a longitudinal percussive movement thereby, valve means for controlling the reciprocation of the piston, said valve means comprising a valve housing disposed in the rst mentioned housing, a main valve and a pilot valve disposed in the valve housing, means interconnecting the pilot valve to the piston to move the pilot valve in timed relation to movement of the piston, means in the pilot valve to alternately direct the well uid to and from one end face of the main valve for actuating the main valve, and a passageway in the valve housing adapted to be alternately opened and closed by the main valve for controlling the application of the well uid to the piston.

References Cited in the tile of this patent UNITED STATES PATENTS 1,861,042 Zublin May 3l, 1932 1,866,335 Youngliug July 5, 1932 2,033,527 Kitching Mar. 10, 1936 

